The theologian and ecumenist Steven Mackie, who has died aged 82, was a friend of mine from student days. He was a man with great intellectual stature and administrative ability, an inquiring and radical mind, and a deep and quiet faith.

He was the son of Robert Mackie, a leading figure in the ecumenical movement and secretary of the World Student Christian Federation, based in Geneva. Born in Edinburgh, Steven went to school in London and Geneva, and, after the family escaped across occupied France in 1940, in Canada. He studied philosophy at Edinburgh University and the Sorbonne, and divinity in Edinburgh.

After three years as chaplain to a Christian college in Madurai, south India, he spent seven years as study secretary of the Student Christian Movement in London. In 1964 he returned to Geneva to be responsible for the World Council of Churches' programme on patterns of ministry and theological education. His international work of organising new thinking about the church's ministry led to the publication of his book Patterns of Ministry in 1969.

He acted as secretary of the committee which arranged the worship at the Assembly of the World Council of Churches at Uppsala in Sweden in 1968. Later he became executive secretary of the department of studies in mission and evangelism of the World Council, and travelled widely.

He was deeply involved with Sodepax, an organisation promoting dialogue between the World Council of Churches and the Catholic Church, with a particular concern over Northern Ireland. Steven paid visits to the province and brought together Protestant and Catholic leaders for a conference in France in 1973.

From 1974 until 1995 he taught practical theology at St Andrew's University. He had a special interest in liberation theology, toured Latin America and made contact with radical theologians there. He took a leading role in Scottish Churches Action for Racial Justice and wrote a range of articles on the relation of theology to such issues as conflict and reconciliation, civil disobedience and social justice.

Steven was an unassuming person and a family man, with a quiet humour that sometimes broke out into vociferous laughter. He is survived by his wife, Annebeth, and their sons, Jamie, Robin and Sandy.